The information transmitted so as to be displayed by devices for displaying information for users is for example, and in a non-limiting manner, audiovisual information broadcast by television channels, audio information or text information.
The data associated with this information are for example data representative of the transmitted audiovisual information and/or data comprising information for configuring a means of decoding the audiovisual information and/or data for indicating the communication network and/or attribute data of the audiovisual information.
The data representative of the audiovisual information are customarily referred to as metadata. The metadata are for example, and in a non-limiting manner, the guide to the transmitted audiovisual programmes, or to a predetermined audiovisual programme, data descriptive of this programme, such as its title, a summary and/or detailed description of the programme, a descriptor of one or more actors appearing in the audiovisual programme or one or more reviews of the programme.
According to the DVB or Digital Video Broadcast standard, it is possible to transmit data representative of the content of broadcast audiovisual programmes. These data conform to the DVB-SI standard. DVB-SI is the acronym for Digital Video Broadcast Service Information. The audiovisual programmes are in this case encoded according to the MPEG or Motion Picture Expert Group standard, and the data representative of the content of the broadcast audiovisual programmes are broadcast in the form of data tables on the same broadcast channel as the audiovisual programmes.
The data tables are transmitted periodically on the broadcast channel so that a receiver may receive them at any moment.
According to this standard, the data associated with the broadcast audiovisual programmes are all broadcast periodically. Moreover, it is not possible for a receiver receiving these data to receive only the latter. Because these data are transmitted on the same channel as the audiovisual programmes, the receiver must receive both the data associated with the audiovisual programmes and the audiovisual programmes, even if only the data associated with the audiovisual programmes are useful to the receiver.
Moreover, the periodic transmission of these data according to this same standard is not adapted to communication networks that do not guarantee a constant bandwidth.
Recommendation RFC 2974, which is known under the acronym SAP, for Session Announcement Protocol, provides for the periodic transmission of session announcement packets on a broadcast channel. These session announcement packets are associated with multimedia conference sessions on the Internet network which are transported over the Internet network on channels that are different from the session announcement packet broadcast channel.
According to this recommendation, a single type of data is transmitted, in this case session announcement packets.
Thus, the solutions proposed in the prior art do not address the problems associated with the transmission of data comprising a plurality of data, in which the importance of the data with respect to one another has to be respected despite variations in the conditions on the communication network.
These same solutions of the prior art do not allow optimization of the time taken to receive data associated with information as a function of their importance.
The aim of the invention is to overcome the drawbacks of the prior art by proposing a method and a device which make it possible to transmit over a communication network data of varying importance while ensuring a minimum time taken to receive these data as a function of their importance with respect to one another.